Muzzle bushing for piston-type power-actuated tool



March 31, 1970 J. BRUNELLE 3,503,549

MUZZLE BUSHING FOR PISTON-TYPE PO'NER-ACTUATED TOOL Filed Sept. 29, 19672 Sheets-Sheet 1 MTW \ INVENTOR: LA wem/cf J. BRL/NELLE Mmm ATTORNEYMarch 31, 1970 L. J. BRUNELLE 3,503,549

MUZZLE BUSHING FOR PISTON-TYPE POWER-ACTUATED TOOL Filed Sept. 29, 19672 Sheets-Sheet 2 INVENTOR I LAWRENCE J. BRUNELLE ATTORNEY United StatesPatent O 3,503,549 MUZZLE RUSHING FOR PISTON-TYIE POWER-ACTUATED TOOLLawrence J. Brunelle, East Haven, Conn., assignor to Olin MathiesonChemical Corporation, a corporation of Virginia Filed Sept. 29, 1967,Ser. No. 671,783 Int. Cl. B25c 7/00 U.S. Cl. 227-149 8 Claims ABSTRACT FTHE DISCLOSURE A muzzle bushing having a longitudinal bore for apiston-type power-actuated tool. The muzzle bushing is provided with aplurality of key members which are peripherally spaced about the muzzlebushing and adapted to extend into the bore. The inner end faces of eachof the key members are provided with a slot for the reception of thehead of a fastener to hold the fastener in a position to be driven bythe piston.

This invention relates generally to power-actuated tools of the pistontype and more particularly to a muzzle Ibushing construction for usewith such tools.

Prior to this invention, it was necessary to provide fasteners whichwere to be driven by a piston actuated power tool with some type ofsupport to properly align the fastener in the muzzle bushing. Suchsupport was usuallyin the form of a washer member positioned around theshank of the fastener or a tip positioned over the pointed end of thefastener and including a tiange for engagement with a bore in the muzzlebushing. This was true whether the tool was of the type wherein thefastener was loaded through the breech end of the tool or of the typewherein the fastener was inserted into the muzzle end.

In view of the above it is the object of this invention to provide amuzzle bushing having means for holding a fastener in proper positionfor the driving operation.

It is another object of this invention to provide a muzzle bushing for apiston type power actuated tool which eliminates the need for fastenersbeing equipped with a special centering an-d holding device such as awasher or the like.

-It is still another object of this invention to provide a poweractuated tool wherein the closing of the muzzle bushing properlypositions a fastener for driving by a piston.

Yet another object of this invention is to provide a fastener holdingattachment for a power actuated tool which insures that the fastenerwill remain parallel to the axis of the piston during the drivingoperation.

These and other objects of the invention may be accomplished inaccordance with a preferred embodiment of the invention through theprovision of escapement keys mounted in the head of a muzzle bushing.The escapement keys are provided with slots to engage and hold the headof the fastener and are adapted to be moved out of the path of the headof the fastener `by the piston immediately before the piston contactsthe head.

The present invention also contemplates the provision of a tool having amuzzle pivotally attached to the re minder of the tool so that the toolcan be broken open and the fastener inserted in the forward end of themuzzle bushing. Cam means are provided which upon closing of the muzzlebushing, urge the fastener into the slots in the escapement keys.

Additional objects and advantages of the present invention will becomeapparent by reference to the following description and to theaccompanying drawings in which:

3,503,549 Patented Mar. 31, 1970 FIGURE l is a vertical sectional viewof the muzzle end of a piston power actuated tool incorporating thefeatures of the present invention;

FIGURE 2 is a sectional view taken along the lines 2-2 of FIGURE l',

FIGURE 3 is a transverse sectional view taken along the lines 2-2 ofFIGURE 3, but with the fastener omitted for the sake of clarity;

FIGURE 4 is a vertical sectional view of the forward end of a pistontype power actuated tool taken during the operation of closing themuzzle bushing; and

FIGURE 5 is a view similar to FIGURE 2 showing the position of theescapement keys and piston during the driving operation.

ln general7 a piston actuated fastening tool incorporating the featuresof the present invention may include an outer housing 2 in which abarrel assembly 4 is mounted for relative reciprocal movement. Thebarrel assembly may include a barrel 6, a liner member 8 positionedtherein and a barrel plug 10 having a reduced bore 12 attached to theforward end of the barrel member 6. A fastener driving member 14 in theform of a piston or the like is mounted for reciprocal movement withinthe barrel assembly with its shank end being supported in the bore 12 ofthe barrel plug 10. .The fastener driving member may be driven byexplosive cartridge means mounted in a breech assembly such as shown inU.S. Patents Nos. 3,066, 302 and 3,172,118 or any other suitable breechassembly, or by any other suitable source of power such as liquidpropellants, combustible mixtures of oxygen and a fuel, etc.

A housing insert 16 is mounted in the internal surface of the housing 2and includes a plurality of circumferentially spaced lugs 18. A retainermember 20 is mounted between the barrel assembly 4 and housing insert 16and includes spaced lugs 22 which coact with lugs 18 on the housinginsert 16 to prevent axial withdrawal of the retainer member 20. Theretainer member 20 further includes an eyelet 24 extending outwardlyfrom the forward end of the housing 2.

A muzzle bushing 26 is mounted within a muzzle bushing housing 28 whichis attached to housing 2 by means of a pivot pin 30 passing through theeyelet 24 which is received within a slot 32 in the bottom of housing28. A suitable spring member 34 may be wrapped around the pivot pin 30and have one end in engagement with the retainer member 20 and the otherend in engagement with the forward end of slot 32 to bias the muzzlebushing housing into its closed position.

The muzzle bushing 26 includes a forward elongated portion 36 and arearward enlarged head 38 having a circumferential groove 40 extendingtheerabout. The `bore 42 of the muzzle bushing is slightly larger thanthe diameter of the shank portion of the driving member 14 to providesuitable clearance for movement.

The rearward face of the head 38 of the muzzle bushing 26 is providedwith a vertically extending slot 44 which tapers to its greatest depthfrom bottom to top. As can be seen in FIGURE 1, the bottom end of theslot 44 intersects the rear face of the head portion at a point abovethe outer edge of the rear face. The top end of the slot 44 intersectsthe forward face at a point slightly above the outer surface of theforward elongated portion 36 ofthe muzzle bushing 26.

The outer circumferential edge of head 38 of the muzzle bushing 26 isprovided with two opposed axially extending slots 45 and 46, the depthof each of said slots 45 and 46 being slightly greater than the depth ofthe circumferential groove 40. The slots 45 and 46 are so positionedthat a plane passing through the midpoint 3 between their sides isperpendicular to a plane passing through the midpoint between the sidesof the slot 44.

A cylindrical bore 48 extends radially through the head 38 of the muzzlebushing 26. The ends of the bore 48 communicate with the slots 45 and 46and the diameter of the bore 48 is substantially the same as the widthof the slots 45 and 46 which in turn is substantially the same as thediameter of the axial bore 42 in the muzzle bushing 26. The axis of thebore 48 lies in a plane passing through the axial midpoint of the head38 of the muzzle bushing 26.

A pair of escapement keys 50 and 52 are mounted on the bore 48 onopposite sides of the axial bore 42. Each of the escapement keys 50 and52 includes a cylindrical body portion 54 so dimensioned as to have asliding tit within the bore 48, and outer oppositely disposed flanges 56and 58 extending in the direction of the axis of slots 45 and 46,respectively. The flanges 56 and 58 form a pair of stop shoulders 60which abut against the bottom of a respective slot 45 and 46 to limitthe movement of the keys 50 and 52 toward the axis of the bore 42.

The keys 50 and 52 are biased into their inner position wherein theshoulders 60 abut against the bottom of a respective slot 45 or 46 byspring means 62. In the preferred embodiment, the spring means 62comprises a band of elastomeric material extending about the head 38 ofthe muzzle bushing 26 in the circumferential groove 40 and engaging theouter surface of each of the keys 50 and 52.

As shown in FIGURE 3, the inner surface of each of the keys 50 and 52 isgenerally arcuate, the radius of the arc being the same as or slightlylarger than the radius of the bore 42 through the muzzle bushing 26. Asshown in FIGURE 2, the inner face of the escapement keys 50 and 52includes, in cross section, a rear forwardly and inwardly taperingportion 64, a straight portion 66 generally parallel to the axis of bore42, and a forward forwardly and outwardly tapering portion 68. Thestraight portion 66 is provided with a slot 70 which is wide enough toreceive the head of a fastener.

When the keys 50 and 52 are in their innermost position, both taperingportions 64 and 68 taper to a point substantially flush with the wall ofthe bore 42 in the muzzle bushing 26. The slot 70 has a at bottom. Thedepth of the slot 70 is such that when the keys 50 and 52 are in theirinnermost position, the bottom surface is substantially tangential withthe wall of the bore 42 of the muzzle bushing 26.

A snap ring 72 is mounted in a suitable groove 74 in the barrel plug andincludes a forwardly extending portion which terminates in a downwardlyextending hook 76 which is normally positioned within the verticallyextending slot 44 in the head 38 of the muzzle bushing 26. When themuzzle bushing 26 is closed as shown in FIGURE 1, the hook terminatesadjacent the bore 42 in the muzzle bushing 26.

To load a fastener 78 in accordance with the described embodiment, Athetool is broken open between the muzzle bushing 26 and housing 2 bypivoting the muzzle bushing 26 clockwise, as viewed in FIGURE 1, aboutpivot pin 30. The fastener 78 may then be loaded from the rearward endof the muzzle bushing 26 into bore 42 wherein it will move forwardlyuntil it is stopped by the tapered surfaces 64 of the escapement keys 50and 52. As the tool is closed by pivoting the muzzle bushing 26counterclockwise, as viewed in FIGURE 4, the forward surface of the hook76 contacts the head 80 of the fastener 78 and urges it forwardly withinthe bore 42 of the muzzle bushing 26, against the tapered surface 64 ofthe keys 50 and 52, moving the keys radially outwardly away from thebore 48. The forward motion of the fastener 78 will continue until thetool is substantially closed and the head 80 of the fastener 78 becomesaligned with the slots 70 in the keys 50 and 52, whereupon the keys 50and 52 will 4 move inwardly so that the head of the fastener iscontained within the slots 70.

When the tool is actuated and the driving member 14 moves forwardlyunder the influence of the power source, it can be seen from FIGURE 5that just as the driving member 14 is about to contact the head of thefastener, it has contacted the tapered surface 64 and the beginning ofthe straight portion 66 of the keys 50 and 52 and moved the keys 50 and52 outwardly away from the bore 42. Accordingly, at this point, thefastener is free to move forwardly in the muzzle bushing 26 under thepropelling force of the driving member 14.

The provision of the escapement keys 50 and 52 provides a positiveretention means for a fastener. This eliminates the counterbore in themuzzle end of the muzzle bushing which is common in piston type toolsfor receiving an enlarged washer member attached to a fastener. Theelimination of the counterbore ensures that the forward end of the shankof the driving member is supported throughout the entire driving strokeas well as providing support for the head of the fastener during thedriving stroke thereby preventing bending of the upper portion of thefastener.

The escapement keys 50 and 52 also hold the fastener in proper alignmentso that when the driving member contacts the fastener, the head of thefastener will be flat against the forward surface of the driving memberensuring that the axis of the fastener will remain substantiallyparallel to the axis of the bore so that the fastener enters the worksurface perpendicular thereto.

Moreover, since the keys 50 and 52 eliminate the need for specialattachments such as washers on the fastener, the cost of an individualfastening operation is greatly reduced.

It is to be understood that the use of the escapement keys, as describedabove, is not limited to tools wherein the fasteners are loaded by hand,but rather such keys may find use in those cases wherein a fastenermagazine is used to automatically feed fasteners into position.

Although reference has been made above to a preferred embodiment of thisinvention, it will be obvious that various alterations and modificationswill readily suggest themselves to those skilled in the art. Accordinglythe scope of this invention should be ascertained from the followingclaims.

What is claimed is:

1. In a power-actuated tool, a barrel, fastener driving means mounted insaid barrel, muzzle bushing means attached to the forward end of saidbarrel and having a bore normally co-axial with said barrel, a pluralityof key mounting bores circumferentially spaced in said muzzle bushingmeans and communicating with said bore, a fastener holding memberincluding a key member mounted in each of said key mounting bores formovement in a direction transverse to the axis of the ybore of saidmuzzle bushing means, each of said key members having an inner end facemovable into and out of said bore of said muzzle bushing means, meansbiasing said key members inwardly in a direction toward the axis of saidmuzzle bushing bore, means limiting the amount of inward movement ofsaid key members, and a fastener receiving slot in the inner end face ofeach of said key members, the inner end face of each of said key membersincluding a tapering portion rearward of said slot, said taperingportion tapering rearwardly of the tool and away from the axis of saidbore of said muzzle bushing means so that when said keys are in theirinnermost position, the rearward edge of said tapering portion istapered away from the axis of the bore to a point at least flush withthe wall defining the bore of said muzzle bushing means.

2. The power-actuated tool of claim 1 wherein said inner end face ofeach of said keys includes a tapering portion forward of said slot, saidtapering portion tapering forwardly and away from the axis of said boreso that when said keys are in the innermost position, the forward edgeof said forward tapering portion is tapered away from the axis of thelbore to a point at least flush with the wall means defining the bore ofthe muzzle bushing.

3. The power-actuated tool of claim 1 wherein said muzzle bushing meansincludes a muzzle bushing housing attached to said barrel and a muzzlebushing mounted within said muzzle bushing housing and having anenlarged head portion and a reduced forwardly extending portion, a pairof axially extending, oppositely disposed grooves in the outer peripheryof said head portion, a key mounting bore associated with each of saidgrooves, said key mounting bores extending in a direction perpendicularto the axis of said muzzle bushing bore with one end of eachcommunicating with one of said grooves and the other end communicatingwith said muzzle bushing bore, a pair of said key members mounted insaid bores, one said key member being positioned on the opposite side ofsaid axis from the other, and said means for limiting the inwardmovement of each of said keys comprises at least one stop shoulderadjacent the outer end of each of said key members and extending in thedirection of said groove so as to abut the bottom surface of said groovewhen the key member is in its innermost position.

4. The power-actuated tool of claim 3 wherein said biasing meanscomprises a peripheral groove extending about the head portion of saidmuzzle bushing, the axis of which lies in the same plane as the axis ofthe key mounting bore, and a band of resilient material positioned insaid groove and abutting the outer end of each of said key members.

5. In a power-actuated tool, a barrel, fastener driving means mounted insaid barrel, muzzle bushing means attached to the forward end of saidbarrel, said muzzle bushing means including a muzzle bushing housingpivotally attached to said housing and a muzzle bushing mounted in saidmuzzle bushing housing and including an enlarged head portion, a reducedforwardly extending portion, and a bore extending therethrough, saidmuzzle bushing means being pivotable between a closed position whereinsaid bore is axially aligned with said barrel and an open positionwherein the rearward opening of said bore is exposed for the loading ofa fastener, a slot in the rearward face of said muzzle bushingintersecting said muzzle bushing bore, fastener holding means mounted insaid muzzle bushing, said fastener holding means including a pluralityof key members peripherally spaced about said muzzle bushing means andmounted therein for movement in a direction transverse to the axis ofthe bore, each of said keys having an inner end face movable into andout of said bore, means biasing said key mem-bers inwardly, meanslimiting the amount of inward movement of said key members, a fastenerreceiving slot in the inner end face of each of said key members, theinner end face of each of said key members including a tapering portionrearward of said slot, said tapering portion tapering rearwardlyrelative to the tool and away from the axis of said bore so that whensaid keys are in their innermost position, the rearward edge of saidtapering portion is tapered away from the axis of the bore to a point atleast flush with the wall deiining the bore, and fastener cam meansattached to said barrel and extending in said muzzle bushing slot forurging the head of a fastener into the fastener receiving slots in saidkey members as the muzzle bushing means is moved into its closedposition.

6. The power-actuated tool of claim S wherein said cam means includes asnap ring secured to the forward end of said barrel, said snap ringincluding a forward and inwardly projecting hook portion, the end ofsaid hook portion terminating at a point ilush with the wall meansdefining the bore in said muzzle bushing means and the forward edgethereof being substantially co-planar with the rearward wall of thefastener receiving slots in said key members when said muzzle bushing isin the closed position.

7. The power-actuated tool of claim 6 wherein said muzzle bushingincludes a pair of axially extending, oppositely disposed grooves in theouter periphery of said head portion and a key mounting bore passingthrough the head portion of said muzzle bushing in a directionperpendicular to the axis of said muzzle bushing bore with the endsthereof communicating with said grooves, a pair of said key membersmounted in said bore, one said key member being positioned on theopposite side of said axis from the other, and said means for limitingthe inward movement of each of said keys comprises at least one stopshoulder adjacent the outer end of each of said key members andextending in the direction of said groove so as to abut the bottomsurface of said groove when the key member is in its innermost position.

8. The power-actuated tool of claim 7 wherein said biasing meanscomprises a peripheral groove extending about the head portion of saidmuzzle bushing, the axis of which lies in the same plane as the axis ofthe key mounting bore, an-d a band of resilient material positioned insaid groove and abutting the outer end of said key members.

References Cited UNITED STATES PATENTS 536,427 3/ 1895 Hayes 227--149853,931 5/1907 Milliken 227-149 916,026 3/ 1909 Sasseman 227-1491,634,226 6/1927 Alibert 227-149 3,409,197 1l/1968 Brack 227-10GRANVILLE Y. CUSTER, JR., Primary Examiner U.S. C1.X.R.

